Cam operated expanding wrench



Patented Feb. 10, 1953 UNITED STATES TENT OFFICE CAM OPERATED EXPANDING WRENCH Vaughn J. Barnett, Charleston, W. Va.

Application November 7, 1949, Serial No. 125,971

3 Claims.

This invention relates to wrenches and particularly to internal expanding wrenches designed for grasping a pipe or other element internally where an ordinary clamping wrench could not be used, or when if used would mar or damage the work.

The object of the present invention is to provide an improved wrench of the type mentioned which may be readily inserted into the bore of a pipe or other article, and which may be turned in either direction as desired, or alternately in opposite directions without removal or resetting the tool.

A further object of the invention is to provide a wrench of the class mentioned which will not distort the circular cross section of the pipe upon which it is being used.

A further object of the invention is to provide a tool of the class stated which shall be of such construction that the necessary leverage may be applied by the use of any type or size of wrench found desirable or convenient.

Other objects will appear hereinafter.

With these objects in view, the invention consists generally in a core having a plurality of oppositely extending eccentric cams, and a body consisting of a pair of cylinder segments surrounding said core and having arcuate eccentric cam grooves to receive the cams on the core. The outer faces of said segments are knurled for the major portion of their length to engage the inner surface of the pipe orother object to be moved, said knurling being such as to firmly grasp the work when the device is turned in either direction. One end of the body is preferably reduced in diameter and provided with an annular groove to receive a split ring for holding the segments in firm but yielding engagement with the core. The invention further consists in various details of construction and combinations of parts, as will be fully described hereinafter and particularly pointed out in the claims.

The invention will be more readily understood by reference to the accompanying drawings, forming a part of this specification and in which,

Fig. 1 is a side elevation of the expanding wrench constituting the subject matter of this application,

Fig. 2 is a top plan view of the same,

Fig. 3 is a longitudinal section on the line 33 of Fig. 2,

Fig. 4 is a transverse section on the line 44 of Fig. 3.

Fig. 5 is a longitudinal section on the line 5-5 of Fig. 1,

Fig. 6 is an elevation of one of the body segments illustrating the inner face thereof, and,

Fig. '7 is a similar view of the lower portion of the opposite segment.

' Referring to the drawings, I0 indicates the cam bearing core of the device, and H and I2 the two cylinder segments respectively, which constitute the body of the device.

The segments II and I2 are similar except for the cam grooves hereinafter described. The outer face of each segment is provided with knurling which preferably extends from the lower or outer end thereof, for the major portion of its length. This knurling is forced against the inner face of the pipe wall when the core is turned, and is of such form as to firmly grip the work when the core is turned in either direction. To this end the knurling consists of a series of longitudinal ridges I3 which are V-shaped in cross-section, and extend radially outwardly from the segments as shown clearly in Figs. 2 and 4 of the drawings.

The upper or inner end Id of the body, beyond the knurling, is preferably reduced in diameter, and the reduced portion is provided with an annular groove I5 to receive a spring ring I6 which holds the segments firmly but yieldingly in place, as will appear more fully hereinafter. Preferably the groove is located adjacent the upper end of the knurling. .1

The core ID is arranged axially within the body; and comprises a cylindrical portion I9 and a plurality of eccentric, diametricallyoppositely ex-. tending cylindrical cams 20, 2I and 22. The cams are preferably formed contiguous to each other, as illustrated in Figs. 3 and 5, although this is not necessary. The intermediate cam 2I, and the cams 2t and 22, extend diametrically oppositely from the portion I9 of the core, and it' should be noted that the width of the cam 2I is substantially equal to the combined widths of the cams 2t and 22 so that the wear of the cam faces on each side of the device will be equal. Preferably the several cams are circular in cross-section but of greater diameter than the portion I9 of the core, and the sides of said cams diametrically opposite the major projecting portions thereof, merge into the face of said core.

The inner faces of the segments II and I2 are cylindrically recessed as at 23 and 24 to receive the portion I9 of the core with a snug working fit; and within the larger or knurled portions thereof, said segments are formed with cam grooves to receive the several cams. The segment II is formed with the cam grooves 25 and 26 for the cams 20 and 22; and the segment I2 in Fig. 2. This facilitates the application of the. actuating lever or wrench to the projection 28,

by preventing the device from slipping too far into the work. This is also a desirable feature when working in a verticaLor sharply inclined pipe to prevent the tool from droppin to a 13051 tion from which it would be difficult or impossible to extract the same.

As shown in the drawings, the eccentricity of the cam portions is comparatively small as the wrench used on a particular job is preferably of a diameter but slightly smaller than the internal diameterof the work, so as to slip easily into the work with but little clearance. To this end the Wrenches are preferably furnished in sets of vari ous sizes to fit within the standard sizes of pipes and/or tubes; although it isto be understood that anyof the wrenches may normally be successfully ,used for a number of different size pipes within reasonable limits. .However, when a pipe is rusted-in position, or ofiers unusual resistance, it is preferable, and generally necessary to use as large a size wrench as can be slipped into the pipe to avoidtransverse distortion of the pipe due to uneven radial pressure.

Also, it is to be understood that the dimensions of. the bore of the segments and the interior cam faces-thereof may be the same through a reasonable range of exterior sizes, so as to be usable with the same core. By this provision, a set of wrench bodies will require a comparatively few cores.

In using the device, a size is selected in which the diameter of the knurled portion, when contracted, is slightlyless than the bore of the Work. Theselected device is then inserted in said bore and the core turned in the direction it is desired toturn the work. By having the contracted'tool aslarge as possible to freely enter the work, a more even pressure is, applied to the work throughout the circumference thereof, thereby avoiding cracking of the work or a distortion of the same.

As the camsw and ZZ-are diametrically oppositextheicam 2|, it is obvious that the greater diameter of the combined cams is on a line intersecting. the centers thereof, that is, on a vertical line with regard to Fig. 2; whereas the lesser diameter .:is at right angles thereto through the centerof .the core. The generatrices of the cylindrical cam facestherefor coincide at the intersection of said faces in'the plane of said lesser diameters. Also, it is to be noted that the meeting 'of the several cam grooves with the adjacent plane faces of the segments 1 I and i2 are straight lines. Therefore, as .the core and the cams thereon are rotated,. the several cams will force the opposite sides of said segments outwardly in angular and diametrically opposite movements relative to-the-planes of said diameter, as they move into the more shallow end zonesof the re- '4 spective grooves. At the same time the ends of the alternate cams will enter the shallow portions of the grooves in the opposite segments, thereby expanding the device to grip the work. As hereinbefore stated, the relative rotary movement of the cams and segments is small.

As the cams extend from opposite sides of the core into the cam grooves, the elements cannot accidentally become separated or moved into an inoperative condition.

When the operation is completed, the core is turn-ed in the opposite direction, and the segments will be retracted by the spring 16. Only a slight turning of the core is necessary to release the grip.

Having described the preferred form of my invention, it is obvious that various modifications thereof maybe made with-out departing from the invention as set forth in the following claims.

I claim:

1..In an expanding wrench, a core havinga plurality of contiguous, oppositely disposed eccentric cams thereon, a pair of cylinder segments surrounding said core and having arcuate eccentric grooves to receive said cams, a plurality of radially extendin gripping ribs arranged longitudinally on the outer surface of said segments, and resilient means holding said segments in yielding engagement with said core.

2. In an expanding pipe wrench, a cylindrical core having a plurality of oppositely extending eccentric cams thereon intermediate the ends of the core, a pair of segments surrounding said core and together having a bore substantially the diameter of said core and eccentric grooves within the bore to receive said cams, knurling on the periphery of said segments, means for yieldingly holding said segments into engagement with said core, and a wrench hold on said core.

3. An expanding pipe wrench comprising a cylindrical core, contiguous cylindrical eccentric cams on said core consisting of an intermediate cam and a pair of end cams having a combined cam surface substantially equal to the cam surface of said intermediate cam, a pair of cylinder segments surrounding said core and having a bore of substantially the same diameter as said core and having arcuate eccentric grooves of substantially the same diameter as said cams to receive the same, a gripping surface formed on the outer faces of said segments, resilient means for holding said segments in engagement with said core, and a wrench hold on said core.

VAUGHN J. BARNETT.

REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 514,477 Kraft Feb. 13, 1894 1,371,642 Olson Mar. 15, 1921 1,522,968 M-illigan Jan. 13, 1925 2,067,442 Frisz Jan. 12, 1937 2,392,427 Stupakofi et al Jan. 8, 1946 FOREIGN PATENTS Number Country Date 638 Great Britain Feb. 16, 1876 118,085 Great Britain Oct. 31, 1918 120,783 Great Britain Nov. 27, 191 8 

